package com.yulan.Tree;

/**
 * 101. 对称二叉树
 * 给定一个二叉树，检查它是否是镜像对称的。
 */
public class LeetCode_101 {

    public boolean isSymmetric(TreeNode root) {
        if(root == null)
            return true;
        return dfs(root.left,root.right);
    }

    public boolean dfs(TreeNode left, TreeNode right){
        if(left == null && right == null)
            return true;
        if(left == null || right == null)
            return false;
        if(left.val!=right.val)
            return false;

        return dfs(left.left,right.right) && dfs(left.right,right.left);
    }
}
